Lab: OWL-DL

Topics

• OWL ontology editing in Protégé.
• Manchester-OWL syntax
• HermiT reasoning.

Useful materials

Readings:

• Protégé 5 Documentation
• OWL2 Primer (from S08): Show Manchester Syntax

Protégé:

• Lab 9 presentation introducing Protégé

Vocabularies and terms (from S09 and same as previous week) - this is for reference: you will not need them all :-):

• Friend of a Friend (FOAF) (if necessary follow the link to the 2004 version)
• Event Ontology (event)
• Time ontology in OWL (time, OWL-time)
• geo: World Geodetic Standard (WGS) 84
• Dublin Core (DC)
• SKOS - Simple Knowledge Organization System Home Page
• Semantic Interlinked Online Communities (SIOC)

Classes and methods

RDF:

• type

RDFS:

• subClassOf, subPropertyOf, domain, range

Basic OWL:

• sameAs, equivalentClass, equivalentProperty, differentFrom, disjointWith, inverseOf
• ReflexiveProperty, IrreflexiveProperty, SymmetricProperty, AsymmetricProperty, TransitiveProperty, FunctionalProperty, InverseFunctionalProperty

Complex OWL:

• oneOf, unionOf, intersectionOf. complementOf
• Restriction, onProperty
• someValuesFrom, allValuesFrom, hasValue
• cardinality, minCardinality, maxCardinality
• qualifiedCardinality, minQualifiedCardinality, maxQualifiedCardinality, onClass

Tasks

Continue extending the InvestigationOntology from the previous exercise.

Task. Stop the reasoner if it is running, and add individuals to represent that:

• Robert Mueller lead the Mueller Investigation.
• Paul Manafort was indicted.
• Elizabeth Prelogar was an investigator.

Task. Start the reasoner again. Have any axioms/triples been added to the ontology?

Task. Can you do a change that makes your ontology inconsistent? (Save often, so you always have a consistent version to revert to :-))

Tip: You can declare two classes as owl:disjointWith one another and set both classes as the rdf:type of some individual.

Task. Revert the ontology back to a consistent state. Use the Individuals by class tab and create the following instances of owl:Thing (for the purpose of the exercise, do not use more specific types!):

• John L Smith (alias Jack Smith)
• Investigation of role in the US Capitol Attack
• Investigation of Trump's handling of grade documents

Create Object property assertions to state that:

• John L Smith is investigating (but not leading) the Investigation of role in the US Capitol Attack
• John L Smith is investigating (but not leading) the Investigation of Trump's handling of grade documents

Task. Start the reasoner again. Does it add more axioms/triples (marked in yellow) to the ontology?

Task With the reasoner still running, use File -> Export inferred axioms as ontology... to save the reasoning results to a new file. Chose a base URI and file name for the new ontology.

(Note that everything from the old ontology is not exported by default. You will have to check off boxes to select what to export. If something is missing, you can try to export again or use Tools -> Merge to combine the old (handmade) and new (inferred by HermiT) ontologies.)

Task. (We assume you have still not added John L Smith as an investigation leader.) Add an axiom to the investigation leader class to make sure that every investigator that is leading an investigation is an investigation leader. Re-run the HermiT reasoner, and check that John L Smith is now an investigation leader,

Task. Use Manchester-OWL syntax to define the class:

• InvestigationTeam, which is a foaf:Group with at least one members, so that all its members are Investigators.

If you have more time

Task: Assume you want to make your ontology public in the LOD cloud.

• What would be an appropriate rdfs:domain for the dc:title property in your ontology?
• What would be the consequence of publishing and ontology with the assertion/triple: (dc:title, rdfs:domain, :Investigation )?
• What would be an appropriate rdfs:domain for the foaf:name property in your ontology? (Tip: you might want to check what the FOAF vocabulary defines: xmlns.com/foaf/0.1/ .)